• KIEAE Journal
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• 제5권4호
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• pp.51-57
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• 2005

For the evaluating daylighting performance, field measurement, scale model test and a set of computer tools can be applied. For the scale model measurements, the sky simulator is a vital facility to represent the desired sky conditions consistently. Recently K university has developed a large size sky simulator, 6m-diameter and 3.7m-height, that is suitable for the international standard. To verify the reliability of the sky simulator, the luminance distribution on the inner sky surface was measured and compared with the CIE standard overcast sky model. It is found that the sky simulator can be reproduced the CIE standard overcast sky condition with 4.3% as mean difference. K university sky simulator is fully validated for usability and accuracy for daylighting researches.

• Journal of the Optical Society of Korea
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• 제19권2호
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• pp.159-164
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• 2015

In the injection-molded light guide plate the replication quality, i.e. the reproduction accuracy, of micro-patterns should be high and uniform over the entire surface area. However technical difficulty in meeting the necessary replication quality arises as the plate size becomes large for TV applications. We propose a simulation technique to optimize the distribution of micro-patterns on a 55-inch injection molded light guide plate considering non-ideal replication quality of micro-patterns. The luminance uniformity could be improved by more than 16% by optimizing the pattern distribution in spite of the same replication quality.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.673-675
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• 2004

This study proposes controller with voltage-compensated drivers for producing gray-scaled pictures on passive matrix organic light emitting diodes (PMOLEDs) panels. The controller includes voltage type drivers so the output impedance of the driver is far less than that of the current-type driver. Its low output impedance provides better electron-optical properties than those of traditional current drivers. A free running clock and a group of counters are applied to the gray-scaled function so that phase lock loop (PLL) circuit can be reduced in the controller. A pre-charge function is used to enhance performance of the luminance of an active OLED pixel. As a result, distribution of the low gray level portion is achieved linear relationship with input data. In this work, the digital part of the proposed controller is implemented using FPGA chips, and analog parts are combined with a digital-analog converter (DAC) and analog switches. A still image is displayed on a $48^{\ast}64$ PMOLEDs panel to assess the luminance performance fir the controller. Based on its cost requirement and luminance performance, the controller is qualified to join the market for driving PMOLEDs panels.

• 소성∙가공
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• 제17권5호
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• pp.322-327
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• 2008

LGP is a key component of LCD back light unit because it determines brightness and sharpness of the display image. Usually, it has optical patterns fabricated on the bottom surface. These optical patterns convert point or line sources placed in the side of LGP to plane source at the top surface by changing the propagating direction of the incident light. In the present paper the LiGA-reflow method was applied to fabricate the LGP mold. Furthermore, the optical simulation considering the replication ratio of pattern height was applied to the pattern design. The optical simulation through systematic correction scheme was adopted to find the optimum distribution of pattern density. Finally, the stamper fabricated by this method was installed in the mold and LGP was produced by injection molding. As a result of luminance measurement for the final product, the average luminance and luminance uniformity was measured 3,180 nit and 84%, respectively. Consequently, the mold fabrication method using the LiGA-reflow and optical simulation(CAE) can save the expense and time compared with the existing fabrication methods(laser ablation and chemical etching).

• 한국통신학회논문지
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• 제27권3A호
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• pp.276-283
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• 2002

본 논문에서는 최대휘도표면을 이용한 색 항상성 알고리즘을 제안한다. 이 방법은 인간의 시각 시스템의 특성을 표현한 선형 모델을 이용한다. 선형 모델에서 가장 중요한 과정은 영상에 존재하는 광원을 추정하는 것이다. 광원을 추정하기 위하여 먼저 영상에 존재하는 가장 밝은 표면의 반사되는 분광 방사 에너지 분포를 추정한다. 그리고 이 표면에 해당하는 분광 반사율을 먼셀색표의 주성분분석을 통하여 추정한다. 추정한 분광 방사 에너지 분포와 분광 반사율을 이용하여 광원을 추정한다. 추정한 광원을 이용하여 영상을 복원할 때 밝기 보정을 위하여 일정한 계수를 사용한다. 실험 결과를 통하여 제안한 최대휘도표면을 이용한 방법이 기존 방법보다 색 항상성에 효과적인 방법임을 증명한다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.269-272
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• 2008

LGP is a key component of LCD back light unit because it determines the brightness and sharpness of display image. Usually, it has optical patterns fabricated on the bottom surface. In the present paper the LiGA-reflow method was applied to fabricate the LGP mold. Furthermore, the optical simulation considering the replication ratio of pattern height was applied to the pattern design. The optical simulation through systematic correction scheme helped find the optimum distribution of pattern density. Finally, the stamper fabricated by this method was installed in the mold and LGP was produced by injection molding. As a result of luminance measurement for the final product, the average luminance and luminance uniformity was measured 3,180 nit and 84%, respectively. Consequently, the mold fabrication method using the LiGA-reflow and optical simulation(CAE) can save the expense and time compared with the existing fabrication methods(laser ablation and chemical etching).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.965-968
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• 2007

The effect of the modification of the front surfaces of flat fluorescent lamps (FFLs) on the light-output distribution has been investigated by using a ray tracing method and several kinds of microlenses. It was found that microlenses have substantial effects on the light-output distribution, which might be used to reduce the number of optical films in the FFL-backlight unit for LCD applications.

• 한국광학회지
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• 제31권4호
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• pp.176-182
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• 2020

서브-미크론 주기의 미세한 회절 격자가 새겨진 도광판을 이용하여 빛을 수직으로 출사시켜 기존 방식에서 사용하는 집광용 프리즘 필름을 대체할 수 있는 가능성에 대하여 연구하였다. 시뮬레이션과 실험을 통해 최적 회절 격자 주기를 결정하였고, 입사되는 빛의 고도각과 방위각에 따라 회절 격자의 투과 모드 효율을 계산하였다. 또한, 회절에 의해 더 많은 빛을 추출할 수 있도록 도광판의 모양과 구성을 제안하여 고도각과 방향각을 최적화하는 두 가지 방식의 효과를 시뮬레이션으로 비교하였다. 광선 추적프로그램을 활용하여 회절 격자 각인 도광판의 휘도 각 분포를 계산하여 실제로 제작된 시제품의 위치별 휘도 각 분포와 비교하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1495-1498
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• 2002

The constrained average method is one of dither methods which combines edge emphasis and grayscale rendition to provide legibility of textual region and proper quality of continuous tone region. How-ever, image quality of continuous tone region is insufficient compared to other dither methods, such as ordered dither methods or the error diffusion method. The constrained average method uses a uniform distribution function to decide number of lit pixels related to the average intensity in a picture area. However, actual distribution of continuous tone region is closer to the Laplacian distribution or triangle distribution. In this paper, we introduce various probability distributions and the actual luminance distribution to decide the threshold value of the constrained average method in order to improve image quality of dithered image.

• Current Optics and Photonics
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• 제8권3호
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• pp.307-312
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• 2024

Measuring the three-dimensional (3D) spatial light intensity distribution of an autostereoscopic multiview 3D display at the user position is time-consuming, as luminance has to be measured at different positions around the user position. This study investigates a method to quickly estimate the 3D distribution at the user position. For this purpose, a measurement setup using a white semitransparent diffusing screen or a two-dimensional (2D) spatial sensor was devised to measure the 2D light intensity distribution at the user position. Furthermore, the 3D spatial light intensity distribution at the user position was estimated from these 2D distributions at different viewing distances. From the estimated 3D distribution, the characteristics of autostereoscopic 3D display performance can be derived and the candidate positions for further accurate measurement can be quickly determined.